Taro Leaf Blight: Disease Assessment, Farmers’ Knowledge and Management Potential of Goatweed Extract in South West Cameroon

Leaf blight disease severely constrains the production of taro (Colocasia esculenta (L.) Schott) in Cameroon. Studies were conducted in seven localities in Fako Division, South West Region of Cameroon to assess the incidence and severity of the disease in taro farms using non-destructive sampling, and to document farmers’ knowledge about it using a structured questionnaire. The fungicidal effect of the aqueous leaf extract of goatweed (Ageratum conyzoides L.) at 0 and 100% concentrations and the chemical fungicide Mancozan was tested in-vitro. Results revealed widespread distribution of the disease in the Region. The incidence (77.9-96.5%) and severity (51.9 – 85.6%) varied significantly (P?0.05) across the localities. The infection rate was classified as high in four localities and very high in three. The farmers were able to identify the disease and understood its effects on taro production but they were not aware of any pesticidal plants for its management. The aqueous leaf extract (100%) of goatweed and Mancozan significantly (P?0.05) inhibited the mycelia growth of the fungus compared to the untreated control (0%). The plant extract had the potential to control the disease although it gave moderate inhibition of the fungus (38.4% at 9 days after exposure) which was not as effective as Mancozan (100% inhibition). Goatweed could be exploited for use as a source of natural fungicide for management of the pathogen. This study provides baseline information for future studies on the disease and recognises it as a major challenge to the sustainable production of taro.